Determination of selected UV filters in indoor dust by matrix solid-phase dispersion and gas chromatography–tandem mass spectrometry

A simple, inexpensive sample preparation procedure, based on the matrix solid-phase dispersion (MSPD) technique, for the determination of six UV filters: 2-ethylhexyl salicylate (EHS), 3,3,5-trimethylcyclohexyl salicylate (Homosalate, HMS), 3-(4-methylbenzylidene) camphor (4-MBC), isoamyl-p-methoxycinnamate (IAMC), 2-ethylhexyl-p-methoxycinnamate (EHMC) and octocrylene (OCR), in dust from indoor environments is presented and the influence of several operational parameters on the extraction performance discussed. Under the final working conditions, sieved samples (0.5 g) were mixed with the same amount of anhydrous sodium sulphate and dispersed with 2 g of octadecyl bonded silica (C18) in a mortar with a pestle. This blend was transferred to a polypropylene solid-phase extraction cartridge containing 2 g of activated silica, as the clean-up co-sorbent. The cartridge was first rinsed with 5 mL of n-hexane and the analytes were then recovered with 4 mL of acetonitrile. This extract was adjusted to 1 mL, filtered and the compounds were determined by gas chromatography combined with tandem mass spectrometry (GC–MS/MS). Recoveries for samples spiked at two different concentrations ranged between 77% and 99%, and the limits of quantification (LOQs) of the method between 10 and 40 ng g⁻¹. Analysis of settled dust from different indoor areas, including private flats, public buildings and vehicle cabins, showed that EHMC and OCR were ubiquitous in this matrix, with maximum concentrations of 15 and 41 μg g⁻¹, respectively. Both UV filters were also quantified in dust reference material SRM 2585 for first time. EHS, 4-MBC and IAMC were detected in some of the analyzed samples, although at lower concentrations than EHMC and OCR.     

Determination of cis-permethrin,trans-permethrin and associated metabolites in rat blood and organs by gas chromatography–ion trap mass spectrometry

An analytical method was developed to measure cis-permethrin and trans-permethrin in different biological rat matrices and fluids (whole blood, red blood cells, plasma, brain, liver, muscle, testes, kidneys, fat and faeces). The method was also suitable for the simultaneous quantification of their associated metabolites [cis-3-(2,2-dichlorovinyl)-2,2-dimethyl-(1-cyclopropane) carboxylic acid (cis-DCCA), trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-(1-cyclopropane) carboxylic acid (trans-DCCA) and 3-phenoxybenzoic acid (3-PBA)] in blood (whole blood, red blood cells, plasma) and liver. The target analytes were derivatised in samples using a methanolic/hydrochloric acid solution and then extracted with toluene. The analysis was performed by gas chromatography, and detection using ion trap tandem mass spectrometry. The selectivity obtained for complex matrices such as rat organs allowed the use of a purification step to be avoided for most of the matrices investigated. In the case of fat, where permethrin is suspected to accumulate, a dedicated purification step was developed. In fluids, the limits of quantification were at the 50 ng/mL level for the parent compounds and 3-PBA and at 25 ng/mL for cis-DCCA and trans-DCCA. For solid matrices excluding fat, the limits of quantification ranged from 50 ng/g for muscle to 100 ng/g for brain and testes for both cis-permethrin and trans-permethrin. The extraction recoveries ranged primarily between 80 and 120 % for the matrix tested. The stability of blood samples was tested through the addition of 1 % v/v formic acid. The methods developed were applied in a toxicokinetic study in adult rats. cis-Permethrin and the metabolites were detected in all corresponding matrices, whereas trans-permethrin was detected only in blood, plasma and faeces.     

Impurity profiling of acetylspiramycin by liquid chromatography–ion trap mass spectrometry

Investigation of acetylspiramycin (ASPM) and its related substances was carried out using a reversed-phase liquid chromatography/tandem mass spectrometry method. The identification of impurities in the ASPM complex was performed with a quadrupole ion trap mass spectrometer, with an electrospray ionization (ESI) source in the positive ion mode which provides MSⁿ capability. A total of 83 compounds were characterized in commercial samples, among which 31 impurities that had never been reported and 31 partially characterized impurities were deduced using the collision-induced dissociation (CID) spectra of major ASPM components as templates. Most of the major impurities arise from the starting materials and the synthesis process. This work provides very useful information for quality control of ASPM and evaluation of its synthesis process.     

Determination of multiple pharmaceutical classes in surface and ground waters by liquid chromatography–ion trap–tandem mass spectrometry

This paper describes development, optimization and application of analytical method for determination and reliable confirmation of nineteen pharmaceuticals from different therapeutic classes (antibiotics—β-lactams, cephalosporines, sulfonamides, macrolides and tetracyclines; benzodiazepines; antiepileptics and analgoantipyretics) in surface and ground waters at ng l⁻¹ levels. Water samples were prepared using solid-phase extraction and extracts were analyzed by liquid chromatography–ion trap–tandem mass spectrometry with electrospray ionization in both positive and negative ionization mode. The efficiency of ten different SPE cartridges to extract diverse compounds from water was tested. The pH-value of the water sample, the volume of elution solvent and the sample volume were optimized. Matrix effect, especially pronounced for cephalexin and metamizole, was eliminated using matrix-matched standards. It was determined that extraction should be performed at pH ∼ 7.5, i.e. without pH adjustment, and at pH 3, depending on the analyte. Azithromycin, doxycycline and acetylsalicylic acid must be extracted in acidic environment, whereas extraction of paracetamol, ampicillin, erythromycin and metamizole should be performed without pH adjustment. Repeatability of the method was generally lower than 20%. The estimated limits of detection were in the range from 0.15 to 12.46 ng l⁻¹. The method was applied to 26 water samples for monitoring of selected drug residues. Results revealed the presence of carbamazepine (80% of water samples), azithromycin (23%), as well as trimethoprim and paracetamol (both 15%). The most striking was the false positive signal of diclofenac in every analyzed water sample. Confirmation of the positive results was performed by repeated injection of the positive sample extracts using confirmatory method with additional transitions.     

Determination of elemental sulfur in coal by gas chromatography – mass spectrometry

A method for the determination of S⁰ in coal based on the extraction with cyclohexane with subsequent quantitative analysis of elemental sulfur in the extract by GC/MS is described. The quantity of elemental sulfur was determined in four coal samples with different distribution of sulfur forms. The effect of solvent and extraction time on the efficiency of sulfur removal was studied. The elemental sulfur extracted from coal occurred in the form of S₆, S₇ and S₈. Calibration solutions were prepared from freshly recrystalized elemental sulfur. It was found that the injection temperature has a crucial influence on the m/z 64 ion chromatogram.     

Determination of fragrance allergens in indoor air by active sampling followed by ultrasound-assisted solvent extraction and gas chromatography–mass spectrometry

Fragrances are ubiquitous pollutants in the environment, present in the most of household products, air fresheners, insecticides and cosmetics. Commercial perfumes may contain hundreds of individual fragrance chemicals. In addition to the widespread use and exposure to fragranced products, many of the raw fragrance materials have limited available health and safety data. Because of their nature as artificial fragrances, inhalation should be considered as an important exposure pathway, especially in indoor environments. In this work, a very simple, fast, and sensitive methodology for the analysis of 24 fragrance allergens in indoor air is presented. Considered compounds include those regulated by the EU Directive, excluding limonene; methyl eugenol was also included due to its toxicity. The proposed methodology is based on the use of a very low amount of adsorbent to retain the target compounds, and the rapid ultrasound-assisted solvent extraction (UAE) using a very low volume of solvent which avoids further extract concentration. Quantification was performed by gas chromatography coupled to mass spectrometry (GC–MS). The influence of main factors involved in the UAE step (type of adsorbent and solvent, solvent volume and extraction time) was studied using an experimental design approach to account for possible factor interactions. Using the optimized procedure, 0.2 m⁻³ air are sampled, analytes are retained on 25 mg Florisil, from which they are extracted by UAE (5 min) with 2 mL ethyl acetate. Linearity was demonstrated in a wide concentration range. Efficiency of the total sampling-extraction process was studied at several concentration levels (1, 5 and 125 μg m⁻³), obtaining quantitative recoveries, and good precision (RSD < 10%). Method detection limits were ≤0.6 μg m⁻³. Finally, the proposed method was applied to real samples collected in indoor environments in which several of the target compounds were determined.     

Determination of polyphenolic compounds by liquid chromatography–mass spectrometry in Thymus species

Polyphenolic compounds represent a wide group of phytochemicals, including well-known subgroups of phenolic acids, flavonoids, natural dyes, lignans etc., which are produced by plants. These natural bioactive compounds possess a variety of beneficial effects including antioxidant and anticarcinogenic activities, protection against coronary diseases as well as antimicrobial properties. Thymus species have already been reported as sources of different phenolic acids and flavonoids. Moreover, the composition and content of flavonoids in Thymus species play important role as taxonomic markers providing distinction of species. High-performance liquid chromatography (HPLC) coupled with diode array detector (DAD) and on-line mass spectrometry (ESI-MS) method was used for analysis. The method was evaluated for a number of validation characteristics (repeatability and intermediate precision, LOD, LOQ, calibration range, and recovery). The polyphenolic pattern of five native Hungarian Thymus species (T. glabrescens Willd., T. pannonicus All., T. praecox Opiz, T. pulegioides L., and T. serpyllum L.) was characterized. The dominant compound was rosmarinic acid, which ranged between 83.49 μg g⁻¹ and 1.436 mg g⁻¹. Other phenolic acids (ferulic acid, caffeic acid and its other derivatives, chlorogenic acid and p-coumaric acids) were present in every examined Thymus species, as well as flavanones: naringenin, eriodictyol and dihydroquercetin; flavones: apigenin and apigenin-7-glucoside, flavonols: quercetin and rutin. The polyphenolic pattern was found to be a useful additional chemotaxonomic tool for classification purposes and determination of the locality of origin.     

Determination of drugs of abuse in water by solid-phase extraction,derivatisation and gas chromatography–ion trap-tandem mass spectrometry

An alternative method for the sensitive determination of several drugs of abuse and some of their metabolites in surface and sewage water samples is proposed. Analytes are concentrated using a solid-phase extraction (SPE) sorbent, converted into the corresponding trimethylsilyl derivatives and selectively determined by gas chromatography (GC) with tandem mass spectrometry (MS/MS) detection. Parameters affecting the performance of extraction, derivatisation and determination steps are systematically investigated. Moreover, the stability of target analytes in sewage water samples is discussed. Under final working conditions, water samples were adjusted at pH 8.5 and concentrated using a 200 mg OASIS HLB SPE cartridge. Analytes were sequentially eluted with ethyl acetate followed by acetone and silylated using N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA). The reaction was completed in 60 min at 80 °C and the mixture injected directly in the GC–MS/MS system without further purification. In most cases, analytes presented a poor stability in sewage water samples; however, once they are submitted to the SPE process, cartridges can be stored at −20 °C for at least 3 months without significant degradation and/or inter-conversion reactions of illicit drugs. The proposed method provided recoveries over 74% and LODs between 0.8 and 15 ng/L for river and treated wastewater samples. In the case of raw wastewater slightly worse recoveries, between 63 and 137%, and similar LODs were attained. Analysis of a limited number of waste and surface water samples confirmed the presence of several illicit drugs in the aquatic environment, with the highest levels and frequency corresponding to benzoylecgonine, the main metabolite of cocaine.     

Determination of diketopiperazines of Burkholderia cepacia CF-66 by gas chromatography–mass spectrometry

Bacteria communicate with each other by a process termed “quorum sensing” (QS), and diffusible, low-molecular-weight chemicals, called signal molecules, are used as the communication languages. In cell-free Burkholderia cepacia CF-66 culture supernatants, five compounds suspected of being signal molecules were identified. The gene (cepI) related with AHLs synthesis were not detected by polymerase chain reaction (PCR) using specific primers. Gas chromatography–mass spectrometry (GC–MS) revealed that these compounds were not AHLs but the diketopiperazines (DKPs) cyclo(Pro–Phe), cyclo(Pro–Tyr), cyclo(Ala–Val), cyclo(Pro–Leu), and cyclo(Pro–Val), all of which were both d and l-type. Four kinds of DKPs had been isolated from other Gram-negative bacteria, but the other was a novel kind discovered in CF-66, and l-cyclo (Pro–Phe) was quantified by GC–MS. It was found that exogenous DKPs had a negative effect on the candidacidal activity of the culture supernatant extracts.     

Screening of pesticides in blood with liquid chromatography–linear ion trap mass spectrometry

In clinical or forensic toxicology, general unknown screening procedures are used to identify as many xenobiotics as possible, belonging to numerous chemical classes. We present here a general unknown screening procedure based on liquid chromatography coupled with use of a single linear ion trap mass spectrometer, and focus on the identification of pesticides and/or metabolites in whole blood. After solid-phase extraction (SPE), the compounds of interest were separated using a reversed-phase column and identified by the mass spectrometer operated first in the full-scan mass spectrometry (MS) mode, in the positive and negative polarities, followed by MS² and MS³ scanning of ions selected in data-dependent acquisition. The total scan time was 2.45 s. Two mass spectral libraries (MS² and MS³), each of 450 spectra, were created for the 320 pesticides and metabolites detected after injection of pure solutions. Robustness of the spectra and matrix effects were studied and were satisfactory for the present application. Detection limits for the 320 compounds were studied by extracting 1 mL spiked blood at concentrations between 10 μg/L and 10 mg/L. If necessary, it was possible to decrease the detection limits of some compounds by 10–100-fold by scanning MS² in only one polarity, owing to a shorter total scan time. However, at the same time, the detection specificity decreased as no confirmation could be recorded in the following MS³ scan and no information could be registered in the other polarity. So, in these rare cases, confirmation by another method was required.     

Determination of synthetic musk in ground water by liquid-liquid extraction-gas chromatography mass spectrometryEI北大核心CSCD

A gas chromatography-mass spectrometry GC-MS method was established to determine three different synthetic musksSMsfrom ground water. Dichloromethane as the extracting solventthe concentrated extracts were tested by GC-MS using the external standard quantitative method. Each sample was extracted three times with 40 mL dichloromethane respectively. The linearity test was carried out in the range of 20.0 to 2000 μµg/L the relative standard deviationRSDRRFof average relative response factor was less than 8.7%and the limits of detectionLODswere in the range of 0.007 to 0.012 μµg/L. The recoveries of three spiked ground water samples were all between 98.1% and 117.0%and the relative standard deviations were less than 13%. Musk xylene in the ground water sample was 0.013 μµg/Land the spiked real sample had the recoveries higher than 80%. This method was suitable for the detection of trace SMs in ground water. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

Determination of polycyclic aromatic hydrocarbons by gas chromatography–mass spectrometry in soils from Southeastern Romania

Gas chromatography–mass spectrometry was used for the determination of 16 priority polycyclic aromatic hydrocarbons (PAHs) in surface soils from seventeen areas in Southeast Romania, including sites placed in the vicinity of Galati iron and steel plant and Lower Prut Meadow natural reserve in Galati County. The total concentration of PAHs (TPAHs) in the investigated soils ranges from 0.003 mg/kg to 38.524 mg/kg dry weight. According to Romanian legislation for trace organic compounds in soils of different uses, the amounts of PAHs in soils from the industrial zone exceed the normal values for the majority of individual PAHs. The lowest concentrations were found in soils sampled from the protected area of Lower Prut Meadow natural reserve and the highest near a zootechnique farm in the Prut River basin, where the alert levels exceeded for the less sensitive area in the case of TPAHs and benzo[b]fluoranthene and for the sensitive area in the case of chrysene, benz[a]anthracene, benzo[k]fluoranthene and benzo[g,h,i]perylene. The sources of PAH contaminating soils are complex, being of both pyrogenic and petrogenic origins.     

Identification of monoacylglycerol regio-isomers by gas chromatography–mass spectrometry

Monoacylglycerols (MAGs) are lipids found in trace amounts in plants and animal tissues. While they are widely used in various industrial applications, accurate determination of the regio-specific distribution is hindered by the lack of stable, commercially available standards. Indeed, unsaturated β-MAG (or Sn-2 MAG) readily undergoes isomerization into α-MAG (acyl chain is attached to the Sn-1 or the Sn-3 position). In the present study, we describe structural elucidation of α- and β-regio-isomers of monopalmitoyl-glycerol (MAG C16:0) as model compounds in their silylated forms using gas chromatography–mass spectrometry (GC–MS) with electronic impact (EI) ionization. MS fragmentation of α-MAG C16:0 is characterized by the loss of methylene(trimethylsilyl)oxonium (103 amu) and the consecutive loss of acyl chain yielding a fragment ion at m/z 205. The fragmentation pattern of β-MAG C16:0 shows a series of diagnostic fragments at m/z 218, 203, 191 and 103 that are not formed from the α-isomer and hereby enable reliable distinction of these regio-isomers. Possible fragmentation scenarios are postulated to explain the formation of these marker ions, which were also applied to characterize the regio-isomer composition of a complex mixture of MAG sample containing n-3 long-chain polyunsaturated fatty acids.     

Characterization of metabolites of sibutramine in primary cultures of rat hepatocytes by liquid chromatography–ion trap mass spectrometry

Liquid chromatography–ion trap mass spectrometry was used for the detection and structural characterization of metabolites of the anti-obesity drug sibutramine. Metabolites were profiled from incubations of sibutramine in primary cultures of rat hepatocytes. In addition, enantioselectivity of sibutramine metabolism was investigated by carrying out separate incubations with (R)- and (S)-sibutramine. As a result, biotransformation profile for sibutramine with rat hepatocytes is proposed. Nineteen metabolites and several of their isomers formed via demethylation, hydroxylation, dehydrogenation, acetylation, attachment of CO₂, and glucuronidation were identified in MS² and MS³ experiments, though the exact position of the functionality, mostly hydroxylation, could not always be determined from the mass spectrometric information. However, clear enantioselective formation was observed for two hydroxyl derivatives and two glucuronide conjugates, indicating that the hydroxyl/glucuronic acid moiety in those structures is close to the chiral center. Most of the metabolites found in this study are new metabolites of sibutramine, which were not previously reported.     

Pharmaceutical trace analysis in aqueous environmental matrices by liquid chromatography–ion trap tandem mass spectrometry

An analytical method based on solid-phase extraction followed by liquid chromatography tandem mass spectrometry with an ion trap analyser was developed and validated for the quantification of a series of pharmaceutical compounds with distinct physical–chemical characteristics in estuarine water samples. Method detection limits were between 0.03 and 16.4 ng/L. The sensitivity and the accuracy obtained associated with the inherent confirmatory potential of ion trap tandem mass spectrometry (IT-MS/MS) validates its success as an environmental analysis tool. Two MS/MS transitions were used to confirm compound identity. Almost all pharmaceuticals were detected at ng/L level in at least one sampling site of the Douro River estuary, Portugal.     

Focused ultrasound solid–liquid extraction and gas chromatography tandem mass spectrometry determination of brominated flame retardants in indoor dust

This study presents a focused ultrasound solid-liquid extraction (FUSLE) and gas chromatography tandem mass spectrometry method for the determination of brominated diphenyl ethers (BDEs), from mono- to hexa-congeners, in indoor dust. This approach provided a simple, fast, and economical method. After the solvent extraction selection, the FUSLE conditions were studied using a central composite design. Finally, the number of extraction cycles was studied. The selected conditions were 8?mL of 3:1 n-hexane-acetone mixture as extraction solvent, at a power of 65% for 20?s. The proposed method allowed accurate determination of BDEs, with recovery values around 100% and detection limits between 0.05 and 0.8?ng?g(-1). It also has advantages over other existing methods in terms of simplicity, analysis time, and solvent consumption. The analysis of several indoor dust samples showed high concentration values of BDEs 47, 99, 100, 153, and 154 in some of the samples, moreover, BDEs 47 and 99 were found in all samples.     

Identification and quantification of glucosinolates in rapeseed using liquid chromatography–ion trap mass spectrometry

A rapid and sensitive method for the speciation and quantification of glucosinolates in rapeseed is described. The method combines liquid chromatography (LC) with ion trap mass spectrometry (ITMS) detection. Electrospray ionization (ESI) has been chosen as the ionization technique for the on-line coupling of LC with ITMS. Glucosinolates are extracted from different rapeseeds with MeOH and the extracts are cleaned-up by solid phase extraction with Florisil cartridges. Aqueous extracts are injected into LC system coupled to an ITMS, leading to accurately quantify eight of the most important glucosinolates in rapeseed, by MS² mode and confirming their structure by MS³ acquisition. All the glucosinolates found in rapeseeds provide good signals corresponding to the deprotonated precursor ion [M-H]⁻. The method is reliable and reproducible, and detection limits range from 0.5 nmol g⁻¹ to 3.7 nmol g⁻¹ when 200 mg of dried seeds of certified reference material are analyzed. Within-day and between-day RSD percentages range between 2.4–14.1% and 3.9–16.9%, respectively. The LC-ESI-ITMS-MS method described here allows for a rapid assessment of these metabolites in rapeseed without a desulfatation step. The overall process has been successfully applied to identify and quantify glucosinolates in rapeseed samples.